Pass the function signature in the detail property of the completion item instead of the label

Based on the gif in the README and the snapshots in https://github.com/Microsoft/vscode/issues/29126#issuecomment-432262123, it looks like this extension is appending the function signature to the function name in the label of the completion item.

This makes the reading of the items hard, especially when the docs are expanded to the side (Hit Ctrl+Space to show/hide the docs once the suggest widget is open)

The CompletionItem has a property called detail. Most extensions use this property to pass the signature. Below is a typsescript example:

I understand the temptation to include the signature as part of the label. It allows the user to choose the right item from the list at a glance. But this is only possible when the function name is small and docs are collapsed. Else, it just adds noise

首先，使用 CompletionItem API documentation 以及 issue 中显示的 completion UI，追踪此扩展构造 VS Code CompletionItem 对象的位置。将函数签名从 item label 移到其 detail property，然后使用 Ctrl+Space 验证 labels 更简洁，同时签名仍显示在展开的文档中。